Kamal El-Hajji tries out a VR headset that offers an interactive tour of the Palace of Westminster. Photograph: Stefan Rousseau/PA

Writing for the House magazine, El-Hajji said he had seen “article after article” about the way the Speaker had treated staff and colleagues working in parliament.

“Due to a considerable lack of evidence supporting these allegations, it seems clear to me that there is a witch-hunt against him, whether it is coming from previously disgruntled staff members or ex colleagues trying to settle old scores of some kind,” he said.

El-Hajji said he believed he spoke for the majority of Commons staff with his support for Bercow. “The reason I use the word ‘we’ instead of ‘me’ is that I have discussed these allegations at length with numerous colleagues and we share the same view – we feel that there is a witch-hunt going on trying to discredit Mr Speaker,” he said.

The serjeant at arms was previously reported to have been uncomfortable with some of the remarks made in the Commons about his appointment. In the House article, El-Hajji said things had “not been very easy” since his appointment in 2015 but Bercow’s backing had given him the confident to remain in the role.

“It certainly felt like there were a lot of unhappy people because of my appointment, and the only viable explanation I can think of is that I am from an ethnic background,” he said. “The support and guidance that Mr Speaker has showed me since I started is probably one of the main factors behind why I am still fulfilling this very prestigious role today.”

“I felt it’s important to stand up for what is right and to show support and solidarity to someone who has done such a great deal for parliament and for the country.”

Bercow has emphatically denied allegations that he bullied his former private secretaries Angus Sinclair and Kate Emms. An inquiry into the bullying allegations was blocked by MPs earlier this year after the Commons standards committee voted three to two against allowing parliament’s watchdog to investigate the claims.

Sinclair told BBC’s Newsnight that Bercow had undermined him in front of other staff, shouted, swore and attempted to physically intimidate him.

His successor, Emms, served as Bercow’s private secretary from May 2010 to February 2011. Newsnight reported Bercow frequently shouted at her, and she was subsequently diagnosed with post-traumatic stress disorder.

David Leakey, who stepped down last year as Black Rod, a ceremonial post in parliament, told Newsnight he had experienced the outbursts of temper described by other former members of Bercow’s staff.

Bercow, who has been Speaker since 2009, said before he took the post he would resign after no longer than nine years – meaning 22 June of this year would be his departure date. However, he is signalled he may stay in post for another year, after he was re-elected in 2017 due to the snap election.